Control system.



H.'L. BEACH. CONTROL SYSTEM. APPLIOATIOH FILED NOV. 8, 1911.

1,119,390, Patented Dec. 1,1914;

INVENTOR.

WITNESSES.-

, ATTORNEY.

UNITED STATES PA JENT OFFICE.

HOWARD L. BEACH, 0F EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A. CORPORATION OF PENN- CONTROL SYSTEM.

Patented Dec. 1, 1914.

Application filed November 8, 1911. Serial No. 659,176.

To all whom it may concern:

. Be it known that I, HOWARD L. BEACH, a

citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have 1nvented a new and useful Improvement n Control Systems, of which the following 1s a specification.

My invention relates to controllers for electric motors and particularly to such con trollers as comprise a plurality of independently operated switches for governing the circuit connections of the motor and lts starting resistance.

The object of my invention is to provide simple and inexpensive means, in a system of the class above indicated, for delaying the action of the resistance-control switches until the current traversing the motor circuit falls below a predetermined value, the current value being automatically varied A for each of the accelerating switches.

Series relay switches for delaying ,the successive action of independently operated control switches are in very general us e end are well understood. \Vhen a single relay switch of this character is employed, the same current value in the motor circuit determines the action of each of the control switches. In some cases, :it is particularly desirable'to delay the action of the control switches located near the end of the series until the motor current has fallen to a lower value than is desirable or necessary in connection with the first switches of the series -ture resistance of the motor.

and, in order to determine independently the closure of each switch, a relay switch has, in some cases, been provided for each of the control switches. According to my present invention, I accomplish substantially the same result with the use of a single relay switch by equipping the relay switch with a shunt winding in multiple circuit relation to a portion of the arma- By this means, the action of the relay switch is not only dependent upon the current traversing the motor circuit, but also upon the electromotive force d rgp in the armature resistance which, of course, gradually decreases to zero as the resistance is short circuited durlng the acceleration of the motor.

By so connecting the windings of the relay switch as to'oppose each other, the relay switch will Obviously remain closed until is considerably reduced and the motor has attalned a considerable speed than will permit the same action when the motor has just been started and the armature resistance is practically included. in the motor circuit. A

The single figure of the accompanying drawing is a diagrammatic view of a control system embodying my invention.

Referring to thfl drawing, the control system here shown comprises an electric motor having an armature 1 and a field magnet winding 2, a motor-starting resistor 3, a plurality of independently operated control switches 4, 5, 6 and 7 a relay switch 8, a master switch 9 and a regulating resistor 10. Assuming that the master switch 9 is closed, energy is supplied from any suitable.

source through line conductor 11, conductor. 12, master switch 9, conductor 13, relay switch 8, conductor 14:, contact terminals 15,

16), conductor 17, etc., as'before. The motor circuit is now established from conductor 11, through armature l, conductor 25, series magnet winding 26 of relay switch 8, conductor 27, resistor sections 3, 3 and 3 conductor 28 and switch 5 to line conductor 23. By reason of the connections just described, the motor is started and sufiicient current traverses the winding 26 to temporarily open relay switch 8. As soon as the motor current is so much reduced as to permit the relay switch 8 to close, although the coil 29 acts quite strongly in opposition to the coil 26 by reason of the large currents traversing the armature resistance, a control circuit is established from conductor 13, through the relay switch, conductor 14, contact terminals 30, contact member 31 (the switch 5 being closed) conductor 32, contact terminals 33,

contact member 34 (the switch t being open) magnet winding 35 of the switch 4 and conductor 22 to conductor 23.

WVhen magnet winding 35 is energized, switch 4[ is closed and contact member 19 is separated from contact terminals 18, thereby interrupting the circuit of magnet winding 21 to permit the switch 5 to open. The re sistance in the armature circuit is thus decreased, only the section 3 of the resistor 3 being now included.

The relay switch 8'is 'provided with a shunt winding 29, a terminal 36 of which is' connected to one terminal of the series winding 26 and a terminal 37 of which is connected through more or less of the variable resistor 10 and the conductor 38 to the junction of resistor section 3 and 3". As the speed of the motor increases, the pull exerted by shunt winding 29 is gradually decreased by reason of the reduction in the electroinotive force drop in the resistance, the value of whichlis greatly reduced, as above indicated.

- The switch 4 is held closed because contact member 34 engages contact terminals 39 and \gcontrol circuit is completed from conductor 13, through said contact memberand terminalsand the winding 35 to condudtors 22 and 23. The reduction of resistance in the armature circuit will usually cause the relay switch '8 to open temporarily and, as soonas the relay switch is again closed, a control circuit is established from conductor 13 through the relay switch, conductor 1a, contact terminals 10, contact member 31 (the switch 5' being open) contact terminals 41,

contact member 19 (the switch '4 being closed) conductor &2, contact terminals 43, contact member 44. (the switch 6 being open) magnet winding of switch 6, and conductor 22 to line conductor 23.

\Vhen magnet winding 45 is energized, switch 6 is closed and contact member 44 engages contact terminals 46 to complete a holding circuit directly from the conductor 13 through said magnet winding to conductor 22. Since switches 4: and 6 are both closed, the resistor sections 3* and 3" are connected in multiple circuit with the section 3 and again the motor current is increased. As soon as the relay switch is again closed, a control circuit is established from con: ductor 13, through conductor 14, contact terminals 10 of switch 5, contact terminals 41 of switch 1, conductors 42, contact terminals 46 contact member 47 (the switch 6 being closed) contact terminals 48, contact 49, (the switch 7 being open) magnet winding 50 of switch 7 and conductor 22 to line conductor 23.= As soon as switch 7 is closed, its magnet winding 50 is connected in a direct holding circuit which is established through contact ninals 51 and contact member 49. The h sh rt circuits the resistor section 3* 'lhedrop in the armature resistance is now comparatively low and, consequently, it is necessary for the current traversing the motor circuit to be materially reduced before the relay switch can open and the last step in the sequence of control taken.

As soon as the relay switch has closed after the switch 7 is closed, control circuit con nections are established from isofiductor 13 to the relay switch, through/conductor 1 1, v contact terminals 15 and contact m mber 16 1 of switch 5, conductor 52, contact erminals 53 and contact member 54 of switch -7, conductor 55, conductor-2 0 and magnet winding 21 of switch 5 to conductors 22 and 23; The switch 5 is thus finally closed and its hold ing circuit is established from conductor 13, through conductor 56, contact terminals 24, contact member 16, conductor 52, contact terminals 53, contact member 54, conductor 55,'etc., as before. A motor circuit is then established directly from conductor 27, through switches 6 and 5, the resistor section being'excluded from the circuit.

When the armature resistance is entirely Q excluded fromthe circuit, the switches 4, 5,

6and 7, being closed, the effect of the shunt winding is m'l. Consequently, since the 1 windings 26 and 29 are acting in opposition I to each other, they may be so designed and the weight of'the moving member of. the

switch be so adjusted, by auxiliary weights or other suitable means, as to secure the most advantageous series of time intervals between the closing of the several acccelerat ing switches. The action of the shunt magnet coil 29 of the relay switch 8 may also be adjusted, by means of the variable resistor' 10, until the acceleration of the motor is accomplished in the most economical and satisfactory manner possible.

The total amount of resistance and the number of independently operated switches are relatively small by reason of the fact that the resistor sections are connected first in a series and then in a multiple circuit relation;

The circuit connections of the system may; be varied within the spirit and scope of my} invention, and I desire that no limitationy' shall be imposed which are not specified ii the appended claims.

I claim as my invention:

1. In a control system, the combinatior with an electric motor, an acceleratin;

' resistance therefor,-and means for grad with an electric motor, an accelerating resistance therefor, and means for gradually reducing the accelerating resistance, of a single means differentially dependent upon the electromotive force drop in the accelerating resistance and the current traversing the motor circuit for automatically delaying the action of the reducing means.

3. In a control system, the combination with an electric motor, an accelerating resistance associated therewith, and separately actuated accelerating switches, of a single means dependent upon the electromotive force drop in the accelerating resistance and the current traversing the motor circuit for automatically delaying the action of the reducing means.

4. In a control system, the combination with an electric motor, an accelerating re sistance, and separately actuated switches for gradually reducing the resistance, of a single means differentially dependent upon the electromotive force drop in the accelerating resistance and the current traversing the motor circuit for automatically delaying the action of the resistance-reducing switches.

5. In a control system, the cinnhination with an electric motor, an armature resistance, and separately actuated acccimaiiing switches, of a relay switch for lei-raring the operation of the several switches, said relay switch having opposing magnet windiw one of which is responsive to the cl ctr motive force drop in the armature icsist-- ance and the other of which is responsiie to the current in the motor circuit.

6. In a control system, the combination with an electric motor, an accelerating re sistance therefor, and means comprising a plurality of switches for gradually reducing the accelerating resistance, of a relay switch for controlling said switches, said relay switch having opposing windings, one of which is in series with the motor armature and the other of which is in parallel relation with said accelerating resistance.

In testimony whereof, I have hereunto subscribed my name this 1st day of Nov.

HOW'ARD L. BEA (1H. Witnesses:

J. H. ALBRECHT, B. B. HINES.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

